Henshaw on /'. occidentalis and P. clarkii. 217 



when differently colored, two specimens rarely agree in the extent 

 of the colored area. In some the white or gray extends in a 

 broad area from the bill to behind the ev r e. In others it is limited 

 to a narrow line reaching only to the eve. 



Although in the table the bills of several specimens are given 

 as straight, it is rare to find two birds with the bills alike, and 

 it is evident that it needs only a large number of specimens to 

 constitute a series leading from one extreme to the other. 



None of the above specimens chance to equal the extreme size 

 often attained by occidentalism and, on the other hand, specimens 

 of clarkii may be had somewhat smaller than here given, vet 

 the larger and smaller individuals in the list are quite within the 

 requirements of size of their respective forms. 



As but eleven specimens are considered here, it is easy to 

 understand to what an unlimited extent the characters of the two 

 forms may be intermingled even when, as in the present instance, 

 the birds are derived from the same locality and taken during the 

 same season. 



Regarding the distinctive distribution of the two forms, we 

 have little to offer save conjecture. The original specimens 

 of both forms came from the Pacific coast, where the two are 

 found together, at least in winter and during the migrations. 

 Dr. Cones says "both varieties occur together in the United 

 States west of the Rocky Mountains." This was probably a 

 slip of the pen, since Dr. Coues clearly could not have intended 

 to imply the occupancy of the same region by forms the dis- 

 parities of which are only to be accounted for on the ground 

 of geographical variation, i.e., variation dependent on difference 

 of locality. 



As a matter of fact, clarkii appears never to have been found 

 in the interior except in fall or winter in Mexico, where, as is 

 well known, birds may, in the dispersion attendant on migration, 

 cross from the Pacific to the Atlantic side and vet be wholly 

 wanting in the interior regions to the northward. 



On the other hand, all the specimens I have seen from the 

 interior, i.e.. between the Rocky Mountains and the Sierras, 

 were typical examples of the large straight-billed form, occiden- 

 talis. and during the breeding season, typical occidentalis may be 

 confined to the interior. Of the breeding range of clarkii 

 nothing is positively known. The fact that the two forms are 



